Carburator and carburation system for internal combustion engines



April 26,. 1955 c. GIANINI 2,706,976 CARBURETOR AND CARBURETION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed March 7, 195] 2 Sheets-Sheet l INVENTOR Como .Gm/w/w.

ATTORNEYS April 26, 1955 c. GIANINI 2,706,976

CARBURETOR AND CARBURETION SYSTEM FOR INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 2 Filed March 7, 1951 INVENTOR CARBURATOR AND CARBURATION SYSTEM FOR INTERNAL COMBUSTION ENGINES Carlo Gianini, Rome, Italy, assignor t Moto Guzzi Societa per Azioni, Como, Italy Application March 7, 1951, Serial No. 214,296 Claims. (Cl. 123119) This inventionprovides a system of carburation for an nternal combustion engine characterized in that the fuel is made to flow un types of carburettors commonly in provided in the suction the engine a throat in which the flow of air and drops. Nevertheless, carburettors constructed on the basis of such informatory principles have considerable defects: In particular, the weight ratio is never maintained at all points of the curve of utilisation, discon- 2,706,976 Patented Apr. 26, 1955 tinuity increasing in the case of rapid opening or closing of the throttle or like control means.

Atomisation of the fuel obtained by sub-atmospheric h speed engines (that is, those having a high capacity), the limited homogeneity of the mixture, caused by defective atomisation, affects the regumovements of certain small auxiliary pumps, which is sutficiently accurate when using a heavy fuel, for example ticularly critical when it is necessary to use, for example,

The mechanical system of carburation forming the subject of the vantages:

(a) Homogenous atomisation, with (b) Perfect mixing of atomised in by the engine, with the formation of an explosive mixture which is also suitable for very rapid cycles.

(0) Atomisation in each cylinder limited solely to the suction phase of that cylinder.

(d) Absence of atomised fuel from the manifolds connecting several cylinder intakes.

(e) Exact adjustment of the amount of fuel even in engines having small cylinder capacity.

(1) Low unit consumption of fuel.

(g) Automatic regulation of the strength of the mixture in any contingency (acceleration, rapid throttling, and so on), even in the case of barometric variations (variations of altitude).

Some embodiments of means vention will be described by way limitation, with reference to the matic drawings,

Figure 1 is the longitudinal section of one embodiment.

igure 1a is a view of a detail.

Figure 2 shows in longitudinal section an alternative embodiment.

Figure 3 shows part of another embodiment, which will be referred to as an atomisation unit.

Figure 4 shows in longitudinal section an alternative embodiment of the mechanism for the regulation of the opening and closing of the discharge of air under pressure.

Figures 5 and Figures 7 and 8 the atomising unit.

Figures 9 to 11 show ing unit.

Referring to Figure 1 of the drawings, a cylinder intake part 1 extends towards the air intake in the form of a tubular conduit 2, in which there is provided at the outer end a normal throttle valve 3 or other suitable regulation means; in a suitable lateral cavity in very fine dispersion. fuel and air drawn 6 show a guillotine valve.

show the particular of two shapes of some dispositions of the atomisthe conduit 2 is provided a seat for a distributing device, constituted essentially by a member suitable for producing an intermittent jet of air under pressure.

As illustrated said device is constituted by a rotary hollow body 4 provided with outlet apertures 5; the body 4 which serves as an air distributor is connected mechanically to the engine and turns in phase with the same. To the interior of the body 4 is supplied a current of air under pressure, derived from a source not shown. The seating in which the body 4 is mounted communicates with the intake part 1 by means of a passage 6 which is suitably directed. Rotation of the body 4 effects of the apertures 5 as they come into register with 6, by which an intermittent discharge of air is caused through the passage 6, the opening and closing being in phase with thg opening and closing of the inlet valve 30 of the cyl- 1n er.

From a fuel collector tube 7 extends in an almost vertical direction into the conduit 2 a jet tube 8 of small bore, from which the fuel issues with a constant flow, by reason of the constant and gauged cross section of the tube 8.

The fuel is kept under pressure by a volumetric supply pump 9, which may be of gear, rotary, or like type. The jet of fuel issuing from jet 8, after having passed freely across the conduit 2 for a short distance in a continuous stream, enters a tube 10, which has much greater section than that of the jet and which returns the fuel to a float chamber 11, which is in communication with the fuel tank (not shown), by means of the pipe 12a, with the aid of a needle valve 12 operated by the float 13 provided to maintain the constant level in the float chamber 11. The pump 9 is disposed to draw 11 through a tube 11a collector 7. differs from and delivers it through a pipe The modification illustrated that shown in Figure 1 in 9 draws the fuel direct from the tank, while a recuperation pump 27 is provided to return the excess fuel continuously to the tank.

At the pump 9, and also when fitted the pump 27, (is driven by the pump 9, and also when fitted the pump driven by the engine and the bore of the jet 8 is constant, the discharge of fuel from the jet 8 is directly proportional to the speed of the engine. The or 8 is disposed vertically, or substantially vertically in a suitable position near the cylinder intake 1, after the valve 3.

The means driving the pump 9 may also drive a small air compressor which supplies the hollow body 4. This compressor may alternatively be driven by a separate transmission, provided that the apparatus is so dimensioned as to produce in all cases sufficient pressure to break up the jet of fuel. It is evident that instead of a single compressor for a multi-cylinder engine there could also be one for each cylinder; in such case the compressor could also be combined with the rotary distributor.

The flow of air which passes through passage 6 from the hollow body 4 is intermittent; the passage 6 is shaped as a nozzle having a gauged section, and discharges into the conduit 2 in a direction transversal and incident to the jet of fuel, against which it impinges in the free zone, between jet 8 and tube 10. Consequently, the jet of fuel is interrupted, broken up, and atomised during the period in which the distributor 4 remains open, namely as long as passage 6 is in communication with the interior of body 4 through one of the apertures 5. Communication is then interrupted as 4 continues to rotate, and the discharge of air under pressure from passage 6 ceases, and the jet of fuel reestablishes its continuity and resumes its course, being received by the tube 10, from which it drops directly into the float chamber 11, if the apparatus is of the construction illustrated in Fig. 1, or is returned direct to the tank by means of the pump 27 in the embodiment illustrated in Figure 2; as both embodiments are substantially identical, the corresponding parts are designated by like references.

The invention further not only provides for the jet of air discharged from 6 to flow intermittently, but also for the distributor 4 and the outlet apertures to be so regulated and proportioned that the discharge is effected solely in the suction phase, when the valve 30 is open and has a duration equal to a predetermined fraction of that phase.

It is evident that if the engine is of the multicylinder type, each cylinder will be provided with one of the units illustrated: in each cylinder therefore, there will be at each instant a constant stream of fuel from a jet 8, while the discharges of air under pressure of t e respective phase with the suction of each respective cylinder.

The invention also provides automatic means for maintaining spired into the cylinder and the fuel atomised therein. In order to achieve this, the following conditions must obviously be satisfied: as the suction periods and also the times of opening of the distributor 4 supplying the jets of air under pressure are inversely proportional to the speed of the engine itself, it is obvious that the delivery of fuel must be constantly proportional to the speed of the engine; in the same way, the delivery of the fuel must obviously be proportional to the density of the air existing in the intake conduit 2. The first condition is complied with by causing the fuel to flow from jets 8 of constant section and providing means for varying the delivery; this is achieved by varying the pressure as a function of the speed of the engine, which is obviously achieved by coupling the pump 9 to the engine itself. In consequence, at any speed, a constant quantity of finely atomised fuel will enter the cylinder on each suction stroke.

It is furthermore necessary to observe that the density of the air is reduced in proportion as the throttle 3 is moved from the position of maximum opening, in which practically atmospheric pressure prevails in conduit 2, to the position of minimum opening (minimum speed), in which case the pressure in the conduit is reduced to about 0.4 mm.

The invention provides a device adapted to vary automatically the speed of delivery of the fuel, in the sense of reducing the same proportionally to the decrease in the density of the air inspired; by any assembly adapted to control the opening of a valve which places the fuel admission tube in partial communication with a branch tube, so as to reduce the delivery of fuel to the jet on reduction of the pressure of the air, or vice versa.

In the embodiments illustrated in Figures 1 and 2, this device is constituted by a closed chamber 14 in which is placed a manometric bellows 15 having one or more deformable elements or equivalent means. Chamber 14 is placed in communication with the conduit 2 downstream of the throttle 3, by means of a conduit 16 of suitable selected section, to ensure that in said chamber a reduced pressure existing in conduit 2 shall be rapidly stabilised, while damping rapid pulsations thereof. The bellows 15 controls the opening of a flow orifice branched from the fuel supply conduit, consequently effecting a gradual drop of pressure and hence the delivery to the jet.

The bellows 15 is fixed at one side to a regulating device 17 supported by one of the walls of chamber 14, while the other side of the bellows is rigidly connected to a needle 19 which passes through the opposite wall of chamber 14 of a gauged aperture. The needle 19 is provided with an end 21 having a gradually increasing throttling section 22, as shown in the detail in Fig. la. When inside the chamber 14 the initial barometric pressure prevails, a terminal cylindrical part 23 of needle 19 completely closes a sharp-edged hole 24 made in a branch of the tube 25, and the pressure of the fuel assumes the maximum value.

When a reduced pressure is created in conduit 2, the bellows 15 expands, causing the needle 19 to advance. This displacement gives rise to the formation of an aperture and hence of an escape of fuel between the throttling section 22 and the orifice 24, this aperture increasing progressively by reason of the shape of section 22, as the vacuum increases. The fuel escaping in increasing amount through the hole 24 is collected by the tube 26 and returned to the float chamber 11 (Figure l) or by a tube 27a to the tank (Figure 2): in this way, continuous correlation of the rate of flow and hence of the delivery to the jet, as a function of the variation of the pressure inside the carburettor is automatically achieved.

The variant shown in Figure 3 is applicable, when 2,706,976 there are intake passages extending in a direction par- The injector of the variant construction shown in allel or substantially parallel, to the axis of the cylinder Fig. 9 sprays the atomized fuel in the midst of the (as in radial engines). tube 2.

In this case a tube 28 for receiving the jet of fuel The tube 2 and the injector 37a are coaxial in the coming from a jet 29 can be incorporated in the wall 5 construction shown in Fig. but the atomized fuel of the intake manifold, thus gaining the advantage of jet and the intaken air stream have opposite directions. leaving completely free the aperture inside the intake The injector 37b of the construction shown in Fig. conduit. 1 is placed in the inferior part of the intake tube 2 The carburettor control throttle 3 of the construction and the axis of the cone of the atomized fuel is transshown in Figs. 1-3, is placed before the injector; if the 10 versal with respect to the motion of the air intaken engine function with a semishut throttle (slow rate) from the cylinder: the injector 37b can be also placed the injector is subjected to the variations of the presso as to spray in a lateral direction with respect to the sure (depressions) which take place behind the throttle intake tube 2.

3 when the aforesaid throttle passes from its maximum The different constructions shown in the drawing are opening to its shutting position, that is to say, a slow selected according to the characteristics and particulars running position. of the engine to which the invention has to be fitted.

The aforementioned depressions are such that the ca- I claim: pacjty of the continuou yet sprayed by the tub 4 in- 1 A system of carburation for an internal combustion creases with rise of the depression. engine, characterised in that the fuel is made to flow The construction shown in Fig. 1 counterbalances under pressure in a continuous stream from a jet of conthis effect which would vary the fuel ratio, by means stant section with a delivery rate which varies as a funcof special devices which originate a depression in the tion of the speed of the engine and of the variation of collecting cup 11, this depression being similar to that the density of the air in the suction conduit, said stream which takes place behind the throttle 3 the aforemenpassing through a chamber in communication w th the tioned duct 10 which has a sufiiciently large section engine intake conduit and said fuel 18 at predetermined allows the abovementioned conditions to be obtained. intervals atomised and intimately mixed with the air for The construction shown in Fig 2 on the contrary comcarburation by the impingement on said stream of a prises a fuel tank (not shown in the drawing) which strong et of air under pressure, the discharge of which of an adequate duct. tion of the suction phase.

The construction shown in the Fig. 4 is such that 2. A carburettor for effecting carburation as claimed the equalization of the aforementioned pressure is no in claim 1, characterised by a continuous circuit for cirmore ne e a y, a the throttle 3a is placed between culation of the fuel, a reservoir, a delivery pump from the jet spray nozzle and the intake or suction valve 30. which extends to each cylinder intake a duct ending with It should also be noted that in determined case the a jet of gauged section directed into a cavity in comof air under pressure intended for atomising the jet of cess fuel disposed opposite the jet, and a conduit re fuel may be effected, instead of by means of rotary cycling the fuel from the collector to the reservoir, and bodies or similar means, directly by the valve control a nozzle associated with means to provide intermittent mechanism (rockers, tappets or the like), the movejets of compressed air directed to impinge on the stream ment of which may effect the opening and the closing of fuel between the jet and the collector. of the means for discharging air to the atomiser. 3. A carburettor according to claim 2, wherein the On account of this device, the pressure variations of 4 means to provide jets of compressed air is a distributor the duct 1 do not interfere with the aforementioned device adapted to regulate the duration, the discharge jet spray nozzle. A slide valve with one gate 3b (Fig. phase, and optionally the pressure of the jets of com- 5) or with two gates 30 (Fig. 6) is more convenient pressed air in relation to the speed of the engine. than a throttle in this special construction A car urettor according to claim 1, including The device which operates the intermittent air out- .30 means for automatically regulating the delivery of the ow may be obtained for instance by means of a piston jet of fuel in order to keep constant the proportion of valve 31 as shown in Fig 4 The said valve 31 is kept fuel to air in the mixture notwithstanding variation of in its seat by means of the spring 32 and shuts the outthe speed of the engine and/or variation of t e pressure pressure. The opening of the valve 31, cuts the fuel 5. A carburettor as claimed in claim 1, wherein the et, the aforementioned opening being in adequate phase delivery 0 the jet of fuel is caused to vary as a function wit t e opening of the valve 7. T e control of the of variation of pressure of the air for carburation, by valve 31 may be had by means of a secondary cam 35 means such as a manometric bellows adapted on variathe said cam 35 being mounted on the same shaft of tion of the pressure in the intake conduit to control a the cam 36, the cam 36 operating the valve 7. valve which elfects gradual opening or closing of an ori- In this case every jet spray nozzle is furnished with fice provided in the fuel delivery duct for diverting a a valve of the same type of 31. part of the fuel stream to the reservoir, the volume of This device does not require the special lubricating said diverted part increasing or decreasing with the apparatus which is necessary for the constructions shown degree of vacuum set up in the intake conduit after the in Figs. 1-3, constructions which comprise a rotating throttle or other regulating means. lining 4. 6. A carburettor as claimed in claim 1, wherein the The cam shaft can also operate little volumetric comcollector serves to conduct the collected excess fuel pr s, the volumetric compressors comprising a cyliny gravity into a float chamber which communicates with der and piston, and causing the intermittent air et to a fuel tank by means of a float valve, and with the be obtained, the said jet being in phase with the opening delivery pump. of the intake valves. The aforesaid construction is not 7. A carburettor as claimed in claim I, wherein the shown in the drawing, its performance being obvious. collector includes a recycling pump by which col- The reversal of the piston can take place by means of lected excess fuel is delivered to a fuel tank. springs; the compression may be operated by secondary 8. A carburettor as claimed in claim 1, wherein the cams with the interposition of adequate devices. Every 7 rate of delivery of the jet of fuel is made to vary injector of this construction is provided with a volumetric as a function of the speed of the engine, by varying the compressor. pressure of the jet, as by mechanically connecting the It must be noted that the et spray nozzle 18 preferdelivery pump and the excess fuel recycling pump, to

ably formed of a single part 37 (Figs. 7-11) and the the engine.

outflow orifice has nozzles 8 which can spray more or so 9. A carburettor as claimed in claim 1, wherein for less open ets. each cylinder of an engine there is provided a fuel The Construction Shown in 8 has a zle 38a jet and an atomising air supply means in phase with the with surrounding holes, the axis of the nozzle convergintake period of the cylinder.

ing with the axis of the injector; a large injector out- 10. A carburettor as claimed in claim 1, wherein a flow cone is thus obtained. distributor for compressed air is constituted by a rotary hollow body with gauged apertures to which air is supplied by a compressor.

11. A carburettor according to claim 1 characterized in that the control and the intermittent outflow devices for the air under pressure comprises a valve controlled by the movement which operates the intake valve.

12. A carburettor according to claim 1 characterized in that the fuel outflow a single part. the outflow orifice of the atomized mixture having a nozzle so shaped as to direct and/ or distribute the jet.

13. A carburettor according to claim 1 characterized in that the motion axis of the atomized fuel has a parallel direction with regard to the stream of the intaken air of the cylinder.

the interior of 14. A carburettor according to claim 1 characterized 15 447,266

air of the cylinder.

References Cited in the file of this patent 10 UNITED STATES PATENTS 1,537,748 Cole May 12, 1925 2,282,458 Conover May 12, 1942 2 426,153 Mock Aug. 19, 1947 Beardsley, Jr. Aug. 17, 1948 

